// Copyright (c) 2026 Storm Dragon
// Authors: Storm Dragon, Angus Kola
// SPDX-License-Identifier: GPL-3.0-or-later

// Package sessionbus selects the same desktop session bus as GLib clients,
// including Python Cthulhu and I38lock, without changing the process environment.
package sessionbus

/*
#cgo pkg-config: gio-2.0
#include <gio/gio.h>
*/
import "C"

import (
	"context"
	"fmt"
	"log/slog"
	"time"
	"unsafe"

	"github.com/godbus/dbus/v5"
)

func sessionAddress() (string, error) {
	var nativeError *C.GError
	address := C.g_dbus_address_get_for_bus_sync(C.G_BUS_TYPE_SESSION, nil, &nativeError)
	if nativeError != nil {
		defer C.g_error_free(nativeError)
		return "", fmt.Errorf("resolve desktop session bus: %s", C.GoString(nativeError.message))
	}
	if address == nil {
		return "", fmt.Errorf("resolve desktop session bus: no address")
	}
	defer C.g_free(C.gpointer(unsafe.Pointer(address)))
	return C.GoString(address), nil
}

// Connect uses GLib's session address discovery and godbus's private connection.
// Bus IDs let debug logs identify mismatched buses without exposing addresses.
func Connect(logger *slog.Logger, component string) (*dbus.Conn, error) {
	address, err := sessionAddress()
	if err != nil {
		return nil, err
	}
	connection, err := dbus.Connect(address)
	if err != nil {
		return nil, err
	}
	if logger != nil && logger.Enabled(context.Background(), slog.LevelDebug) {
		ctx, cancel := context.WithTimeout(context.Background(), 500*time.Millisecond)
		defer cancel()
		var busID string
		if err := connection.BusObject().CallWithContext(ctx, "org.freedesktop.DBus.GetId", 0).Store(&busID); err != nil {
			logger.Debug("query session bus identity", "component", component, "error", err)
		} else {
			logger.Debug("connected to session bus", "component", component, "bus_id", busID)
		}
	}
	return connection, nil
}